NEW ORLEANS — An 80-lead electrocardiographic body-surface mapping system significantly improved detection of acute myocardial infarction and unstable angina, compared with the standard 12-lead ECG.
Use of the 80-lead technology—branded as PRIME ECG—in emergency department patients with chest pain and an abnormal but nondiagnostic 12-lead ECG should lead to markedly better risk stratification and earlier implementation of appropriate therapy, Dr. James W. Hoekstra said at the annual meeting of the Society for Academic Emergency Medicine.
The 80-lead system includes a single-use disposable vest with 64 embedded anterior and 16 posterior chest leads, along with a computer that enables physicians to view the data as integrated three-dimensional color maps. The system also can display each lead individually. The rationale for the FDA-approved 80-lead technology is that the standard 12-lead ECG has major blind spots, most notably in detecting MIs that are posterior, inferior, right-sided, or high lateral, said Dr. Hoekstra, professor and chairman of the emergency medicine department at Wake Forest University, Winston-Salem, N.C.
The OCCULT MI (Optimal Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction) trial was a large observational study. in 1,830 patients who presented to a dozen major participating U.S. EDs with chest pain and a history highly suggestive of an ischemic cardiovascular event.
Patients initially received a standard 12-lead ECG. If it showed evidence of an ST-elevation MI, patients were sent to the cardiac catheterization laboratory. If it was nondiagnostic, patients received the 80-lead PRIME ECG. Because the study was observational, physicians remained blinded to the 80-lead ECG findings.
The 12-lead ECG detected STEMI in 88 patients, while the 80-lead ECG increased that yield by 27.5%. But because physicians were unaware of the 80-lead ECG findings, STEMI patients detected by the novel technology were subjected to a conservative and delayed catheterization strategy. As a result of the delay, 30-day mortality in STEMI patients detected by 12-lead ECG was 8.0%, compared with 12.5% in those identified by 80-lead ECG.
The study implication is that if physicians had access to the 80-lead ECG findings—as in real-world clinical practice—the patients with occult STEMI would have been diagnosed and revascularized more expeditiously, with correspondingly better outcomes, said Dr. Hoekstra.
OCCULT MI included 202 patients with unstable angina and 206 with non-ST-elevation MI. The sensitivity of 12-lead ECG for detection of NSTEMI was 10.7%, compared with 19.4% for the 80-lead ECG. The 80-lead system identified an additional 18 NSTEMI patients not detected by 12-lead ECG.
The 12-lead ECG had 7.1% sensitivity for detection of unstable angina, compared with 12.3% for the 80-lead system. That represented a 73% improvement over the 12-lead ECG. The 80-lead system identified an additional 21 unstable angina patients. Specificity for ACS was high with both types of ECG, but favored the 12-lead ECG, which had 96.4% specificity for NSTEMI, compared with 93.9% for the 80-lead ECG, a statistically significant difference.
Dr. Hoekstra disclosed that he serves as a consultant to Heartscape Technologies, Inc., which funded OCCULT MI and markets the PRIME ECG.
The mapping system creates full-color images of the heart's electrical activity. Courtesy Heartscape Technologies, Inc.